ROME—A fast-food fight has broken out in the shadow of Florence’s magnificent, centuries-old Duomo.

The bitter battle is pitting McDonald’s Corp. against Florence’s city fathers, who—in the name of a beautification campaign—are trying to keep the fast-food giant from opening a new restaurant a stone’s throw from Brunelleschi’s soaring dome.

The war has its roots in new licensing rules that Florence’s city hall passed in January with the aim of beating back the proliferation of mini-markets, kebab shops and convenience stores that serve throngs of flip-flop clad tourists in the city of Dante and Michelangelo.

The new rules favor food outlets serving up Tuscan fare, but subject all others to an exacting scorecard to determine whether they make the grade to grace Florence’s historic center.

When news broke in the spring that McDonald’s, which has long struggled to win Italians over to Big Macs and gigantic milk shakes, was seeking permission to open its 10th restaurant in Florence alongside the Duomo, a local insurgency ensued. More than 24,000 people signed an online petition in protest. Some launched an event dubbed Lampredotto Pride—named after a Florentine specialty made from cow’s stomach—and marched into the city center brandishing local products and dishes.

“Florentines have been pushed out of the historic center, which is already crammed with stores offering shoddy, and often expensive, food,” said Gilberto Bertini, who headed the protest.

Eager to lure some of the roughly three million tourists visiting the Duomo each year, McDonald’s was willing to rewrite its own rule book to win over the city.

Wait staff would serve customers at tables, thus eliminating takeaway orders to deflect the city’s fears of hordes of picnicking tourists. The Americans also promised to source 80% of ingredients locally, including 100 tons of Tuscany’s prided Chianina beef for burgers.

But city officials were nonetheless merciless in grading the newfangled McDonald’s, granting failing grades to the project on originality and locally sourced products. McDonald’s even put forth a proposal for a completely new store design that retained only its golden arches: the idea earned a 5.4 out of 10.

Last month, McDonald’s struck back, filing an €18-million ($19.8-million) lawsuit against the city that branded the official response as “a manifest injustice.” A profanity that the mayor of Florence used publicly to describe McDonald’s earlier this year betrayed “a belligerent contrariety,” the suit says.

“We completely agree that the cultural and artistic heritage and the Italian historical town centers have to be protected,” McDonald’s said in a statement. “But we cannot accept discriminatory regulations that damage the freedom of private initiative without helping anyone.”

The city, which has beaten back other challenges to its new rules, remains unmoved. “It’s a not a blanket rejection of McDonald’s,” says Giovanni Bettarini, Florence’s deputy head of tourism and economic development. “It’s just a rejection of that specific project.”

The battle in Florence reflects tensions elsewhere in Italy, where local authorities are struggling to defend centuries-old town centers from hordes of tourists. In its complaint in Florence, McDonald’s in turn threatens other suits should other towns pass similar local identity regulations.

Indeed, residents in Rome are now challenging the opening of a 6,000-square-foot McDonald’s just outside St. Peter’s Square on the grounds that it violates local rules aimed at protecting Rome’s mom-and-pop trattorie and restaurants.

Locals, including cardinals, view the new McDonald’s as further degradation of the Eternal City, which saw tourist numbers rise by a third to almost 14 million between 2010 and 2015.

“The problem is not McDonald’s per se,” said Moreno Prosperi, who is leading the protest by Roman residents. “The area is already saturated with fast-food outlets, cheap souvenir shops and convenience stores.” Elsewhere in Rome, residents around Piazza Navona are still seething over McDonald’s’ opening of a new outlet there few weeks ago.

Rome city officials say the vagueness of existing rules gives them no grounds to deny the authorization, but they are considering an overhaul of the regulations aimed at preserving traditional businesses in historic areas.

Italy has long been a challenging market for McDonald’s. When it opened one of its first Italian restaurants in Rome’s Piazza di Spagna in 1986, demonstrators bearing plates of spaghetti protested. The event helped prod Carlo Petrini to launch his Slow Food movement that year. Today, McDonald’s has 540 restaurants in Italy with about €1 billion in revenue. But that is just 2% of Italy’s casual dining market.

In food-savvy France, by comparison, the American chain has also sparked protests over the years—most infamously in 1999, when a group of farmers sacked a McDonald’s under construction in the country’s southwest. But its similar moves to adapt to the French market, such as using homegrown products and selling “McBaguettes” and macarons, have found more success: More than 1,300 McDonald’s outlets operate in France, although its population of nearly 67 million people is only 10% larger than Italy’s 60.7 million.

Some in Italy say the anti-McDonald’s campaign is misguided. Massimiliano Tonelli, content manager of the Gambero Rosso, an Italian bible on quality food and wine, said the proliferation of gelato parlors and Italian-owned eateries serving mediocre Italian fare is a far greater threat to the country’s culinary heritage.

“When tourists eat fake or shoddy Italian food, the harm to our cuisine’s image is huge,” Tonelli said. “If those tourists had eaten at a fast-food restaurant, there would have been no such harm.”